This study analyzed through-thickness distribution of residual stress in a 106 mm ultra-thick TC4 titanium alloy electron beam welded(EBW)joint after post weld heat treatment(PWHT)using X-ray diffraction(XRD)and deep-...This study analyzed through-thickness distribution of residual stress in a 106 mm ultra-thick TC4 titanium alloy electron beam welded(EBW)joint after post weld heat treatment(PWHT)using X-ray diffraction(XRD)and deep-hole drilling(DHD)methods,and investigated the microstructure and mechanical properties.During the PWHT at 600℃,a phase transformation(β→α)occurred in the EBW joint and affected the residual stress distribution and mechanical properties.The surface residual stress was mainly compressive stress,while the internal residual stress was mainly tensile stress in the welded joint.For the as-welded joint,the absolute value of surface residual stress was higher than the absolute value of internal residual stress.After PWHT,the residual stress in the treated joint was substantially reduced compared to the as-welded joint,particularly the surface stress,which relieved from−425 to−90 MPa.However,the residual stress relief effect had minimal positive impact on the internal region at 600℃.PWHT resulted in a shift of the joint fracture location from the fusion zone(FZ)to the base metal(BM),and therefore exerted no noticeable effect on the joint strength,but increased the joint elongation significantly.This study provides valuable insights into the regulation of residual stress distribution of ultra-thick titanium alloy plates.展开更多
Rechargeable aqueous Zn-MoO_(x)batteries are promising energy storage devices with high theoretical specific capacity and low cost.However,MoO_(3)cathodes suffer drastic capacity decay during the initial discharging/c...Rechargeable aqueous Zn-MoO_(x)batteries are promising energy storage devices with high theoretical specific capacity and low cost.However,MoO_(3)cathodes suffer drastic capacity decay during the initial discharging/charging process in conventional electrolytes,resulting in a short cycle life and challenging the development of Zn-MoO_(x)batteries.Here we comprehensively investigate the dissolution mechanism of MoO_(3)cathodes and innovatively introduce a polymer to inhibit the irreversible processes.Our findings reveal that this capacity decay originates from the irreversible Zn^(2+)/H^(+)co-intercalation/extraction process in aqueous electrolytes.Even worse,during Zn^(2+)intercalation,the formed Zn_(x)MoO_(3-x)intermediate phase with lower valence states(Mo^(5+)/Mo^(4+))experiences severe dissolution in aqueous environments.To address these challenges,we developed a first instance of coating a polyaniline(PANI)shell around the MoO_(3)nanorod effectively inhibiting these irreversible processes and protecting structural integrity during long-term cycling.Detailed structural analysis and theoretical calculations indicate that=N-groups in PANI@MoO_(3-x)simultaneously weaken H+adsorption and enhance Zn^(2+)adsorption,which endowed the PANI@MoO_(3-x)cathode with reversible Zn^(2+)/H^(+)intercalation/extraction.Consequently,the obtained PANI@MoO_(3-x)cathode delivers an excellent discharge capacity of 316.86 mA h g^(-1)at 0.1 A g^(-1)and prolonged cycling stability of 75.49%capacity retention after 1000 cycles at 5 A g^(-1).This work addresses the critical issues associated with MoO_(3)cathodes and significantly advances the understanding of competitive multi-ion energy storage mechanisms in aqueous Zn-MoO_(3)batteries.展开更多
As core components of precision-guided projectiles,projectile-borne components are highly susceptible to failure or even damage in complex high-overload environments,thereby significantly compromising launch reliabili...As core components of precision-guided projectiles,projectile-borne components are highly susceptible to failure or even damage in complex high-overload environments,thereby significantly compromising launch reliability and safety.However,accurately characterizing the mechanical behavior of propellants remains challenging due to the limitations in the current internal ballistic theory and the constraints of large-scale artillery firing experiments.This complicates the high-precision numerical modeling of projectile launch,and obstructs investigations into the failure mechanisms of projectile-borne components.Therefore,this paper identifies propellant parameters using the computational inverse method under uncertainty,further establishes high-precision numerical models of projectile launch,and explores the failure mechanisms of projectile-borne components in complex high-overload environments.First,a projectile launching experiment is meticulously designed and executed to obtain the breech pressure and muzzle velocity.Then,a general simulation model is built,and the powder burn model is used to simulate the ignition and combustion.Subsequently,the propellant parameters are effectively identified with the computational inverse method by the combination of the experiments and simulations.A high-precision numerical model of projectile launch is modified with the parameters validated by another experiment,and the high-overload characteristics during projectile launch are thoroughly analyzed based on this model.Finally,the high-overload characteristics of projectile-borne components are analyzed to elucidate the stress variation laws and to reveal the failure mechanisms influenced by time and spatial locations.This research provides an effective method for perfectly identifying propellant parameters and building high-precision numerical models of projectile launch.Additionally,it provides significant guidance for the anti-high overload design and analysis of projectile-borne components.展开更多
Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging becaus...Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.展开更多
目的探讨多模式预康复策略对老年衰弱结直肠癌手术患者的功能状态及短期预后的影响。方法回顾性收集2021年1月—2023年6月接受手术治疗的老年衰弱结直肠癌患者的临床资料,所有患者均采用加速康复外科(enhanced recovery after surgery,E...目的探讨多模式预康复策略对老年衰弱结直肠癌手术患者的功能状态及短期预后的影响。方法回顾性收集2021年1月—2023年6月接受手术治疗的老年衰弱结直肠癌患者的临床资料,所有患者均采用加速康复外科(enhanced recovery after surgery,ERAS)路径管理,依据是否实行多模式预康复分为预康复组和对照组。采用1∶2倾向性评分匹配平衡组间基线差异所致的混杂偏倚,比较匹配后两组患者资料,卡钳值设为0.1。主要观察指标为术后4周6分钟步行距离(6-minute walk distance,6MWD);次要观察指标为衰弱指数(frail index,FI)、手术时间、术中出血量、术后并发症、术后住院时间、术后30 d再入院率/再手术率及术后90 d死亡率。结果本研究最终共纳入182例患者(上海交通大学医学院附属第九人民医院62例,临沂市人民医院61例,聊城市人民医院59例),预康复组31例,对照组151例。经1∶2匹配后成功匹配93例患者,预康复组31例,对照组62例。术后4周预康复组6MWD改善值大于对照组[(46.3±33.7)m vs(7.6±30.2)m,P=0.002],预康复组6MWD改善值>20 m的患者数占比多于对照组(55%vs 9.9%,P=0.033)。FI预康复组小于对照组(中位数2 vs 3,P=0.024)。两组间手术时间、并发症发生率、术后30 d再入院率/再手术率及术后90 d死亡率差异无统计学意义(P>0.05)。术后住院时间预康复组长于对照组[(14.0±4.3)d vs(11.3±4.2)d,P=0.007]。结论多模式预康复策略未增加围手术期风险,有助于改善老年衰弱结直肠癌患者术后功能状态,可能提高患者对手术应激的耐受性,从而使其更好地从ERAS中获益。展开更多
The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion res...The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion resistance of Q235 carbon steel.Scanning electron microscopy results indicated that the CeO_(2) grains were rod-like and ellipsoidal in shape,and the distribution pattern of BTA was analyzed by energy dispersive spectroscope.The dynamic potential polarization curve proved the excellent corrosion resistance of the composite epoxy resin with CeO_(2) and BTA co-addition,and electrochemical impedance spectroscopy test analysis indicated the significantly enhanced long-term corrosion protection performance of the composite coating.And the optimal protective performance was provided by the coating containing 0.3%(mass)CeO_(2) and 20%(mass)BTA,which was attributed to the barrier performance of CeO_(2) particles and the chemical barrier effect of BTA.The formation of corrosion products was analyzed using X-ray diffraction.In addition,the corrosion resistance mechanism of the coating was also discussed in detail.展开更多
Amorphous alloys,with unique atomic structures and metastable nature,are treated as superior candi-dates for environmental wastewater remediation due to their superior catalytic capabilities.Given the strong demand fo...Amorphous alloys,with unique atomic structures and metastable nature,are treated as superior candi-dates for environmental wastewater remediation due to their superior catalytic capabilities.Given the strong demand for environmental protection,the field of amorphous alloys in wastewater treatment has great development prospects,and numerous research results have been published in recent years.As a promising catalyst,it was demonstrated that amorphous alloys could exhibit many excellent proper-ties in wastewater treatment,such as high catalytic efficiency,easily adjustable parameters and reliable sustainability.This paper aims to summarize recent research trends regarding amorphous alloys in the field of catalysis,focusing on the preparation methods,physical performance,catalytic mechanisms and environmental application.Meanwhile,this review also investigates the challenges encountered and fu-ture perspectives of amorphous alloys,offering new research opportunities to enlarge their applicability spectra.展开更多
Low-permeability reservoirs are generally characterized by low porosity and low permeability.Obtaining high production using the traditional method is technologically challenging because it yields a low reservoir reco...Low-permeability reservoirs are generally characterized by low porosity and low permeability.Obtaining high production using the traditional method is technologically challenging because it yields a low reservoir recovery factor.In recent years,hydraulic fracturing technology is widely applied for efficiently exploiting and developing low-permeability reservoirs using a low-viscosity fluid as a fracturing fluid.However,the transportation of the proppant is inefficient in the low-viscosity fluid,and the proppant has a low piling-up height in fracture channels.These key challenges restrict the fluid(natural gas or oil)flow in fracture channels and their functional flow areas,reducing the profits of hydrocarbon exploitation.This study aimed to explore and develop a novel dandelion-bionic proppant by modifying the surface of the proppant and the fiber.Its structure was similar to that of dandelion seeds,and it had high transport and stacking efficiency in low-viscosity liquids compared with the traditional proppant.Moreover,the transportation efficiency of this newly developed proppant was investigated experimentally using six different types of fracture models(tortuous fracture model,rough fracture model,narrow fracture model,complex fracture model,large-scale single fracture model,and small-scale single fracture model).Experimental results indicated that,compared with the traditional proppant,the transportation efficiency and the packing area of the dandelion-based bionic proppant significantly improved in tap water or low-viscosity fluid.Compared with the traditional proppant,the dandelionbased bionic proppant had 0.1-4 times longer transportation length,0.3-5 times higher piling-up height,and 2-10 times larger placement area.The newly developed proppant also had some other extraordinary features.The tortuosity of the fracture did not influence the transportation of the novel proppant.This proppant could easily enter the branch fracture and narrow fracture with a high packing area in rough surface fractures.Based on the aforementioned characteristics,this novel proppant technique could improve the proppant transportation efficiency in the low-viscosity fracturing fluid and increase the ability of the proppant to enter the secondary fracture.This study might provide a new solution for effectively exploiting low-permeability hydrocarbon reservoirs.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFC2810700)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2021193)the Science and Technology Cooperation Project between Jilin Province and Chinese Academy of Sciences(No.2024SYHZ0032).
文摘This study analyzed through-thickness distribution of residual stress in a 106 mm ultra-thick TC4 titanium alloy electron beam welded(EBW)joint after post weld heat treatment(PWHT)using X-ray diffraction(XRD)and deep-hole drilling(DHD)methods,and investigated the microstructure and mechanical properties.During the PWHT at 600℃,a phase transformation(β→α)occurred in the EBW joint and affected the residual stress distribution and mechanical properties.The surface residual stress was mainly compressive stress,while the internal residual stress was mainly tensile stress in the welded joint.For the as-welded joint,the absolute value of surface residual stress was higher than the absolute value of internal residual stress.After PWHT,the residual stress in the treated joint was substantially reduced compared to the as-welded joint,particularly the surface stress,which relieved from−425 to−90 MPa.However,the residual stress relief effect had minimal positive impact on the internal region at 600℃.PWHT resulted in a shift of the joint fracture location from the fusion zone(FZ)to the base metal(BM),and therefore exerted no noticeable effect on the joint strength,but increased the joint elongation significantly.This study provides valuable insights into the regulation of residual stress distribution of ultra-thick titanium alloy plates.
基金supported by National Natural Science Foundation of China(22209064,52071171,and 52202248)the Fundamental Research Funds for Public Universities in Liaoning(LJKLJ202434)+6 种基金the Australian Research Council(ARC)through Future Fellowship(FT210100298)Discovery Project(DP220100603)Linkage Project(LP210200504,LP220100088,LP230200897)Industrial Transformation Research Hub(IH240100009)schemesthe Australian Government through the Cooperative Research Centres Projects(CRCPXIII000077)the Australian Renewable Energy Agency(ARENA)as part of ARENA’s Transformative Research Accelerating Commercialisation Program(TM021)European Commission’s Australia-Spain Network for Innovation and Research Excellence(AuSpire)。
文摘Rechargeable aqueous Zn-MoO_(x)batteries are promising energy storage devices with high theoretical specific capacity and low cost.However,MoO_(3)cathodes suffer drastic capacity decay during the initial discharging/charging process in conventional electrolytes,resulting in a short cycle life and challenging the development of Zn-MoO_(x)batteries.Here we comprehensively investigate the dissolution mechanism of MoO_(3)cathodes and innovatively introduce a polymer to inhibit the irreversible processes.Our findings reveal that this capacity decay originates from the irreversible Zn^(2+)/H^(+)co-intercalation/extraction process in aqueous electrolytes.Even worse,during Zn^(2+)intercalation,the formed Zn_(x)MoO_(3-x)intermediate phase with lower valence states(Mo^(5+)/Mo^(4+))experiences severe dissolution in aqueous environments.To address these challenges,we developed a first instance of coating a polyaniline(PANI)shell around the MoO_(3)nanorod effectively inhibiting these irreversible processes and protecting structural integrity during long-term cycling.Detailed structural analysis and theoretical calculations indicate that=N-groups in PANI@MoO_(3-x)simultaneously weaken H+adsorption and enhance Zn^(2+)adsorption,which endowed the PANI@MoO_(3-x)cathode with reversible Zn^(2+)/H^(+)intercalation/extraction.Consequently,the obtained PANI@MoO_(3-x)cathode delivers an excellent discharge capacity of 316.86 mA h g^(-1)at 0.1 A g^(-1)and prolonged cycling stability of 75.49%capacity retention after 1000 cycles at 5 A g^(-1).This work addresses the critical issues associated with MoO_(3)cathodes and significantly advances the understanding of competitive multi-ion energy storage mechanisms in aqueous Zn-MoO_(3)batteries.
基金Project supported by the National Natural Science Foundation of China (No. 12302435)。
文摘As core components of precision-guided projectiles,projectile-borne components are highly susceptible to failure or even damage in complex high-overload environments,thereby significantly compromising launch reliability and safety.However,accurately characterizing the mechanical behavior of propellants remains challenging due to the limitations in the current internal ballistic theory and the constraints of large-scale artillery firing experiments.This complicates the high-precision numerical modeling of projectile launch,and obstructs investigations into the failure mechanisms of projectile-borne components.Therefore,this paper identifies propellant parameters using the computational inverse method under uncertainty,further establishes high-precision numerical models of projectile launch,and explores the failure mechanisms of projectile-borne components in complex high-overload environments.First,a projectile launching experiment is meticulously designed and executed to obtain the breech pressure and muzzle velocity.Then,a general simulation model is built,and the powder burn model is used to simulate the ignition and combustion.Subsequently,the propellant parameters are effectively identified with the computational inverse method by the combination of the experiments and simulations.A high-precision numerical model of projectile launch is modified with the parameters validated by another experiment,and the high-overload characteristics during projectile launch are thoroughly analyzed based on this model.Finally,the high-overload characteristics of projectile-borne components are analyzed to elucidate the stress variation laws and to reveal the failure mechanisms influenced by time and spatial locations.This research provides an effective method for perfectly identifying propellant parameters and building high-precision numerical models of projectile launch.Additionally,it provides significant guidance for the anti-high overload design and analysis of projectile-borne components.
基金financially supported by the China Postdoctoral Science Foundation(No.2024M751205)。
文摘Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.
基金financially supported by the National Natural Science Foundation of China(22178242)the Shanxi Provincial Key Research and Development Project(202102040201009).
文摘The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion resistance of Q235 carbon steel.Scanning electron microscopy results indicated that the CeO_(2) grains were rod-like and ellipsoidal in shape,and the distribution pattern of BTA was analyzed by energy dispersive spectroscope.The dynamic potential polarization curve proved the excellent corrosion resistance of the composite epoxy resin with CeO_(2) and BTA co-addition,and electrochemical impedance spectroscopy test analysis indicated the significantly enhanced long-term corrosion protection performance of the composite coating.And the optimal protective performance was provided by the coating containing 0.3%(mass)CeO_(2) and 20%(mass)BTA,which was attributed to the barrier performance of CeO_(2) particles and the chemical barrier effect of BTA.The formation of corrosion products was analyzed using X-ray diffraction.In addition,the corrosion resistance mechanism of the coating was also discussed in detail.
基金National Natural Science Foundation of China (No. 51672028)National Water Project of China (No. 2018ZX07105–001) for financial support
文摘Amorphous alloys,with unique atomic structures and metastable nature,are treated as superior candi-dates for environmental wastewater remediation due to their superior catalytic capabilities.Given the strong demand for environmental protection,the field of amorphous alloys in wastewater treatment has great development prospects,and numerous research results have been published in recent years.As a promising catalyst,it was demonstrated that amorphous alloys could exhibit many excellent proper-ties in wastewater treatment,such as high catalytic efficiency,easily adjustable parameters and reliable sustainability.This paper aims to summarize recent research trends regarding amorphous alloys in the field of catalysis,focusing on the preparation methods,physical performance,catalytic mechanisms and environmental application.Meanwhile,this review also investigates the challenges encountered and fu-ture perspectives of amorphous alloys,offering new research opportunities to enlarge their applicability spectra.
基金supported by the Natural Science Foundation of Sichuan“Settlement and Transport Mechanism of Biomimetic Dandelion Proppant in Fracture” (No.23NSFSC5596)the China Postdoctoral Science Foundation (No.2023M742904)。
文摘Low-permeability reservoirs are generally characterized by low porosity and low permeability.Obtaining high production using the traditional method is technologically challenging because it yields a low reservoir recovery factor.In recent years,hydraulic fracturing technology is widely applied for efficiently exploiting and developing low-permeability reservoirs using a low-viscosity fluid as a fracturing fluid.However,the transportation of the proppant is inefficient in the low-viscosity fluid,and the proppant has a low piling-up height in fracture channels.These key challenges restrict the fluid(natural gas or oil)flow in fracture channels and their functional flow areas,reducing the profits of hydrocarbon exploitation.This study aimed to explore and develop a novel dandelion-bionic proppant by modifying the surface of the proppant and the fiber.Its structure was similar to that of dandelion seeds,and it had high transport and stacking efficiency in low-viscosity liquids compared with the traditional proppant.Moreover,the transportation efficiency of this newly developed proppant was investigated experimentally using six different types of fracture models(tortuous fracture model,rough fracture model,narrow fracture model,complex fracture model,large-scale single fracture model,and small-scale single fracture model).Experimental results indicated that,compared with the traditional proppant,the transportation efficiency and the packing area of the dandelion-based bionic proppant significantly improved in tap water or low-viscosity fluid.Compared with the traditional proppant,the dandelionbased bionic proppant had 0.1-4 times longer transportation length,0.3-5 times higher piling-up height,and 2-10 times larger placement area.The newly developed proppant also had some other extraordinary features.The tortuosity of the fracture did not influence the transportation of the novel proppant.This proppant could easily enter the branch fracture and narrow fracture with a high packing area in rough surface fractures.Based on the aforementioned characteristics,this novel proppant technique could improve the proppant transportation efficiency in the low-viscosity fracturing fluid and increase the ability of the proppant to enter the secondary fracture.This study might provide a new solution for effectively exploiting low-permeability hydrocarbon reservoirs.
文摘目的 近年来,Transformer跟踪器取得突破性的进展,其中自注意力机制发挥了重要作用。当前,自注意力机制中独立关联计算易导致权重不明显现象,限制了跟踪方法性能。为此,提出了一种融合上下文感知注意力的Transformer目标跟踪方法。方法 首先,引入SwinTransformer(hierarchical vision Transformer using shifted windows)以提取视觉特征,利用跨尺度策略整合深层与浅层的特征信息,提高网络对复杂场景中目标表征能力。其次,构建了基于上下文感知注意力的编解码器,充分融合模板特征和搜索特征。上下文感知注意力使用嵌套注意计算,加入分配权重的目标掩码,可有效抑制由相关性计算不准确导致的噪声。最后,使用角点预测头估计目标边界框,通过相似度分数结果更新模板图像。结果 在TrackingNet(large-scale object tracking dataset)、LaSOT(large-scale single object tracking)和GOT-10K(generic object tracking benchmark)等多个公开数据集上开展大量测试,本文方法均取得了优异性能。在GOT-10K上平均重叠率达到73.9%,在所有对比方法中排在第1位;在LaSOT上的AUC(area under curve)得分和精准度为0.687、0.749,与性能第2的ToMP(transforming model prediction for tracking)相比分别提高了1.1%和2.7%;在TrackingNet上的AUC得分和精准度为0.831、0.807,较第2名分别高出0.8%和0.3%。结论 所提方法利用上下文感知注意力聚焦特征序列中的目标信息,提高了向量交互的精确性,可有效应对快速运动、相似物干扰等问题,提升了跟踪性能。
